Conventionally, an electric double layer capacitor has been proposed, the electric double layer capacitor is mountable on the surface of a printed wiring board of a mobile phone and so on. An example of such technology is described in the Japanese published unexamined patent application no. 2005-210064.
FIG. 3 is a cross-section diagram to explain the configuration of a conventional electric double layer capacitor. The conventional electric double layer capacitor is hereafter explained in reference to FIG. 3.
In the conventional electric double layer capacitor, as shown in FIG. 3, an electric double layer capacitor element 102, which sandwiches a separator 102c between a cathode 102a and an anode 102b, is arranged inside a sealed container 101 comprising a lid 101a and a concaved containing portion 101b comprised of ceramics, such as alumina.
On the inner bottom face of the containing portion 101b, a first conductive layer 103 comprised of a tungsten is formed, and a insulating layer 104 comprised of ceramics, such as alumina, is further formed and covers the first conductive layer 103. On the insulating layer 104, an opening portion 104a, which reaches from the surface of insulating layer 104 to the first conductive layer 103, is formed, and a second conductive layer 105 comprised of a valve metal, such as aluminum, or a carbon is formed on the first conductive layer 103 inside the opening portion 104a. A conductive adhesive 107 is formed on the insulating layer 104 and the second conductive layer 105, and a cathode 102a is connected to the second conductive layer 105 through the conductive adhesive 107. Also, the first conductive layer 103 penetrates through the side wall of the containing portion 101b, and is connected to a connecting terminal 108 that reaches from the side face to the lower face of the containing portion 101b. 
A conductive adhesive 109 is formed on the anode 102b, and the anode 102b is connected to a forth conductive layer 110 comprised of gold and nickel formed on the lower face of lid 101a through the conductive property adhesive 109. Also, the fourth conductive layer 110 extends between the lid 101a and the container portion 101b, and is connected to a connecting terminal 111 that reaches from the side face to the lower face of the containing portion 101b. 
Also, the inside a container 101 is filled with electrolytic solution (not shown) to sufficiently impregnate the cathode 102a and anode 102b. In this way, the conventional electric double layer capacitor is configured.
In the conventional electric double layer capacitor, the first conductive layer 103 comprised of tungsten is likely to undergo an anode corrosion, thus the first conductive layer 103 is coated with the insulating layer 104 comprised of ceramic to inhibit the corrosion. Also, by filling the second conductive layer 105 that connects the first conductive layer 103 with the cathode 102a inside the opening portion 104a of insulating layer 104, the first conductive layer 103 is not exposed to the electrolytic solution. Further, in the conventional electric double layer capacitor, the second conductive layer 105 is comprised of a valve metal, such as aluminum, or a carbon which are anode corrosion inhibiting. Consequently, in the conventional electric double layer capacitor, the second conductive layer 105 and the first conductive layer 103 are hard to dissolve even when a high voltage of approximately 3V is applied to the cathode.
However, in the conventional electric double layer capacitor described above, due to an occurrence of cracks on the second conductive layer 105 comprised of the valve metal, such as aluminum, or carbon, and occurrence of gaps between the opening portion 104a and the second conductive layer 105 when heated by processes, such as reflow soldering, there are problems of a penetration of the electrolytic solution into such cracks or gaps. In this case, there is an issue of an increase in internal resistance for the conventional electric double layer capacitor described above because a contact failure due to anode corrosion is prone to occur in the first conductive layer 103.
The present invention is made to solve issues as described above, and one of the objectives for the present invention is to provide an electric double layer capacitor whose internal resistance is less likely to increase.